Jack,
The short answer is no, it wasn't. I was far to junior in the company at the time to have such needs. I don't think I would have had the imagination to think up such a stunt.
Was it fraud, only a court could decide that, the aircraft left blox " for the purpose of taking‑off".
I have never understood the "what's done in practice" as some kind of justification for non-compliance. We all exceed the speed limits on the roads from time to time, no matter how often you do it, "what's done in practice" doesn't make it legal.
There are enough ways of getting into strife with our aviation regulations, without giving the Airstapo a free kick.
Tootle pip!!